The most significant advantage is that it’s conducted in plain view, making it nearly impossible for an employee to tamper with the sample, and because it analyzes the drug metabolites inside the hair shaft, external contaminants or adulterants have absolutely no effect. Another advantage is that it offers a far longer detection window than mouth swab, which is typically only a few days, or urinalysis, which is typically a few weeks.
How does this test work?
This drug test can be conducted literally anywhere because no fluid samples are collected and no privacy is required. During this test, a collection specialist will first review identifying information of the test subject. The collection specialist will then use a pair of scissors to collect approximately 100 strands of hair from the crown of the test subject’s head. If there are concerns that taking the hair sample will leave an empty or bald-looking patch, several samples can be collected from multiple locations.
The hair sample must be collected from as close to the surface of the scalp as possible to enable the laboratory to identify recent drug use. While technically drug use can be identified throughout the entire sample, we are usually most interested in the 90 days prior to the test, so the end of the strand will usually be discarded and only a short section of the base will be used for testing.
Once the hair sample is collected, it is placed in a tamper-proof plastic bag and sent to the lab for testing. During testing, specific substances in the proteins of the hair follicle are measured. The cortex of hair strands stores deposits that remain in the body after a drug has metabolized in the system, and by examining the cortex of the hair strands, the examiner can often conclude:
- What types of drugs were used
- Roughly when the drug was used
- If drug use was a repeated pattern
Hair follicle drug testing is one of the most preferred types of drug tests among employers because this test provides an in-depth look at the prior drug-related behavior of potential job candidates or employees.
- Offers a longer detection window than other drug test types
- Shows historical drug-use behavior and patterns
- Almost impossible to manipulate by the test taker
- Detects drugs that metabolize quickly, such as cocaine
- Taken most seriously be test takers, which can deter candidates who know they will not pass
- Works even on people with no head hair because body hair can also be used
- Can be a little more costly than basic urine analysis tests
- Results can take a little longer to obtain
- Not a good way to test for impairment or very recent drug usage
- Not an approved method for the DOT drug testing
- May not always show only sporadic drug use
Drugs that can be identified by a hair follicle drug test
A hair drug test can detect various legal and illegal substances, within a window of a few days after drug use up to 90 days, including, but not limited to:
- Opiates / opioids
- Synthetic marijuana
- Ecstasy (MDMA)
- Crystal meth
- Rohypnol (roofies)
Are there scenarios where it cannot be used?
There are certain scenarios when a hair follicle drug test cannot be used, which is a major limitation in areas other than pre-employment screening. Because it can take time for the drugs used to show up in the hair, the hair has to grow beyond the scalp to show results. In other words, you would not be able to take a hair sample from someone who used methamphetamine for the first time today or yesterday and see that they used the drug. It would be feasible to expect it to take five to seven days for the hair to grow enough for the drug to show up as a positive after analysis.
Because of this limitation, they are not federally recognized by the Department of Transportation. Therefore, if you would be testing an employed driver after an accident on the job, for example, a hair drug test would not suffice as evidence of whether the driver was under the influence. Even still, hair follicle tests can be highly advantageous for employers who hire drivers and operators for thorough pre-hiring screening.
It is often assumed that if a person has no hair on their head, this method worn’t work, but this is actually not the case, because body hair can also be used as a sample. However, the rate of body hair growth is varied greatly compared to head hair growth, so the results of the test can be a little less reliable or a little less in-depth. Additionally, hair drug tests can be performed no matter what type of treatment their hair has undergone. Therefore, if a person’s hair has been chemically treated with perming agents, dyes, or other styling products, it will not affect the outcome of the test results.
Overall, this is the most effective and comprehensive methods for determining whether your employees or prospects have used drugs.